Okay - I tore half my car apart last night for some R&D and found a few things....

-- Under the center console (next to the ebrake if you pull the whole thing up) are two UNUSED wiring connectors, clipped into the console so they won't rattle. One is a purple/violet antenna connector...it goes into the harness and disappears. A continuity test indicates that it is grounded with the FM radio antenna but the center pin is different. I dunno if it has anything to do with NAV or its there in case I had the comfort access option. The other connector is a huge funky connector with only four pins installed which has BL,GN,BR,RT/GN wires coming out of it. Its in the perfect location for the i-drive controler, but the wiring color codes don't jive with my WDS diagram. The connector doesn't even come close to fitting the i-drive controller I have either, Hmm....

-- I have another wiring loom I got with my SatNav system...its confusing since I seem to think its exactly the same as the one in my car. Yes...so far, I think the dash looms are identical to i-drive cars. The audio system harness appears to be the same also! No different part numbers on realoem.com either. I've labeled all of the connections I've located so far. If I could find the unused display connector (somewhere behind the instrument cluster I think) for the i-drive lcd screen, I'd be sure its the same harness...more R&D to follow...

-- The connector that goes into the back of my stock Professional radio is the same that goes into the back of the SatNav computer. I put it in and it fired up the CD motors, and lit up the button backlighting, but nogo. (although I didn't have the display hooked up either.)

-- Bottom line, I think there are three main things so far to deal with: a) Antenna: if a separate antenna lead to the nav antenna was run from SatNav computer to sharkfin (or wherever the harness ends) I think we'd be in business. It looks like the antenna for the SOS system contains the GPS guts. b) The wiring for the i-drive controller needs to be located (or adapted if the wiring I found is it.) c) Display wiring: the display has two connectors, one fat multi-pin wire to the SatNav computer (easy) and another 12-pin connector, which at this time is MIA. I still think its hidden up in the dash somewhere, taped to the harness so it won't rattle.

I'm sure there are many more issues, but these are the beginning ones I located thus far.

Rev2Live- I'm pretty sure that the CCC/SatNav computer is completely self-contained within the radio..the entire system is in the box and is routed up to the display and uses the i-drive controller. The radio does use the Logic7 amplifier tho, as far as I know. There is no other computer in the trunk (this may be completely different if you have the TV option though...) The SatNav computer does look like it has a two-part module put together (sort of like the 53/54 you were talking about), but its not the same thing. Its a complete set that doesn't come apart. Looks similar tho..